1. Field of the Invention
This invention involves the field of technology pertaining to the growing of plants hydroponically, i.e., with enriched water and air. The invention relates to a method and apparatus for optimizing the yield per hydroponic greenhouse by controlling all of the variables which affect plant growth and to maximize greenhouse space utilization.
2. Description of the Prior Art
A common problem in many hydroponic plant growing operations is that the amount of space between individual plants is fixed and maintained from the date of planting until harvesting. This can result in an underutilization of available growing space and consequently the costs of production are greater than would be the case if available growing space were used in a more efficient manner.
Most growers of hydroponic products grow plants either in troughs at fixed spacing with nutrient water supplied at one or two places and drained at one or two ends, or in stationary pots, grow-blocks, or other devices providing physical support with the nutrient being dripped on, flowed through, or flowed around the support.
Prior attempts to alleviate the spacing problem in hydroponic farming are shown in Haub et al U.S. Pat. Nos. 4,337,986 and 4,216,618. These patents disclose a variable pitch screw arrangement for increasing the spacing between plants in accordance with their growth rate. However, these variable pitch screw arrangements are used in conjunction with a trough system in which the troughs are placed in parallel relation to each other. While this system allows for increased spacing between rows, it does not provide for automatic spacing between adjacent plants within a trough as they grow.
Davis et al U.S. Pat. No. 4,028,847 provides spacing between rows of plants by the use of a divergent track system. Young plants are first tended in growth chambers and then moved to tracks or troughs. This system does not provide for increased spacing between adjacent plants as they mature.
Another known system uses divergent troughs with a variable pitch screw arrangement which moves the plants along the troughs at gradually widening x-y spacings as they grow. This method provides appropriate space for leaves, but not for roots, which are confined within the available space of the trough. The roots tend to dam the free flow of nutrient water, causing the roots to turn brown, harbor disease, have less uniform development, etc. In addition, because this system is virtually inaccessible from the bottom, there is no way of removing sick plants without breaking off the roots, which remain in the trough and breed more disease.